Maintaining consistent and uniform tones is a desired goal in image forming apparatus and devices. For example, it can be desirable for an image to appear the same no matter which rendering system renders the image and no matter how many times an image is rendered on a particular system. The image should exhibit, for example, the same lightness or hue each time it is rendered on a given system and no matter on which system it is rendered. For this reason, rendering engines, such as print engines in a printing system, are put through a validation process in order to evaluate whether the print engines realize appropriate color reproducibility.
In the color validation process, a plurality of color measurement pages, each of the plurality of color measurement pages having a plurality of color patches, are printed and measured by a measuring device, for example, a color sensing device in the image forming apparatus, and then each of colors measured by the measuring device is compared with a corresponding target color.
If one of the measured colors does not match the corresponding target color, color corrections can then be made to the image forming apparatus.
As for a high-end printer in which high color reproducibility is required, thousands of color patches can be printed in one color validation process, and the validation process can be repeated with a short interval.